If you track when players or dispensers/droppers drop items, you would be able to tell the difference between 'intentionally' marked mobs by dropping them pumpkins etc, vs mobs that have inadvertently picked up dirt, or a chicken egg or something.

This would probably provide saner defaults.

I can add a config to allow whitelisting certain items etc but it needs further testing and might hog performance. My goal is to keep it as barebones as possible. I'll see how it goes thanks for the suggestion.